Change MaybeApplyTransformation to return a boolean (#3555)

Also refactor the code accordingly.

source/fuzz/fuzzer_pass.h

diff --git a/source/fuzz/fuzzer_pass.h b/source/fuzz/fuzzer_pass.h
index f8acff2..0603c94 100644
--- a/source/fuzz/fuzzer_pass.h
+++ b/source/fuzz/fuzzer_pass.h
@@ -105,13 +105,16 @@
 
   // A generic helper for applying a transformation only if it is applicable.
   // If it is applicable, the transformation is applied and then added to the
-  // sequence of applied transformations. Otherwise, nothing happens.
-  void MaybeApplyTransformation(const Transformation& transformation) {
+  // sequence of applied transformations and the function returns true.
+  // Otherwise, the function returns false.
+  bool MaybeApplyTransformation(const Transformation& transformation) {
     if (transformation.IsApplicable(GetIRContext(),
                                     *GetTransformationContext())) {
       transformation.Apply(GetIRContext(), GetTransformationContext());
       *GetTransformations()->add_transformation() = transformation.ToMessage();
+      return true;
     }
+    return false;
   }
 
   // Returns the id of an OpTypeBool instruction.  If such an instruction does

source/fuzz/fuzzer_pass_permute_blocks.cpp

diff --git a/source/fuzz/fuzzer_pass_permute_blocks.cpp b/source/fuzz/fuzzer_pass_permute_blocks.cpp
index 27a2d67..24c16fb 100644
--- a/source/fuzz/fuzzer_pass_permute_blocks.cpp
+++ b/source/fuzz/fuzzer_pass_permute_blocks.cpp
@@ -67,12 +67,7 @@
       // down indefinitely.
       while (true) {
         TransformationMoveBlockDown transformation(*id);
-        if (transformation.IsApplicable(GetIRContext(),
-                                        *GetTransformationContext())) {
-          transformation.Apply(GetIRContext(), GetTransformationContext());
-          *GetTransformations()->add_transformation() =
-              transformation.ToMessage();
-        } else {
+        if (!MaybeApplyTransformation(transformation)) {
           break;
         }
       }